lecture 20: regulation of respiration Flashcards by Tanya Thibault

true or false: Rate of alveolar ventilation (VA) is adjusted almost
exactly to demands of the body such that PO2 and
PCO2 in arterial blood are hardly ever altered

true

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Rate of alveolar ventilation (VA) is adjusted to what

almost
exactly to demands of the body such that PO2 and
PCO2 in arterial blood are hardly ever altered

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are the PO2 and PCO2 in arterial blood usually alterned

no , usually rate of alverolar ventilationn is adjusted to almost exactly demands of the body

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what are the 3 elements involved in regulation of respiration

Basic control of respiration
Chemical control of respiration
Peripheral chemoreceptor control of respiration

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what are the functions of sensors in terms of regulation of respiration snf give examples

– Gather information

– Stretch receptors, peripheral chemoreceptors, baroreceptors, etc

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WHAT IS THE FFUNCTIONN OF central controllers in terms of regulation of respiration and give examples

– Integrate signals

– Respiratory center (dorsal, ventral, pneumotaxic groups)

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what is an example of effectots of regulation of resrpiration

respiratory muscles 
(ex: diaphragm, intercostals)

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basic Control of basic rhythm of respiration is generated by what

– Generated by the respiratory center (central controller)

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where is the respiratory center

Mainly in dorsal respiratory group of neurons

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true or false; Neurons emits repetitive bursts of inspiratory neuronal action
potentials (cause is unknown)

true

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explain ramp signal

begins weakly (low frequency of impulses)
impulse frequency increases gradually in a ramp manner for 2 seconds, which results in gradual expansion of lungs and chest
excitation then suddenly ceases for next 3 seconds, so that elastic recoil of lung occurs for expiration

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the neurons part of the respirtory center induce whatt types of discharges and whatt does that mean

Induces rhythmical inspiratory discharges (diaphragmatic

contraction)

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inhibtion of the excitory signal from the respiratory center does what

promotes expiratiton

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what are the 2 ways to control inspiratory ramp

1) Control of rate of increase of ramp signal

2) Control of limiting point at which ramp
signal suddenly ceases

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increased ramp slope promotes what

faster fillimng of air Vt in lungs

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Early ramp signal cessation shortens or increases duration of inspiration

shortens

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early ramp signal cessation shortens what

shortens duration of inspiration as well as duration of expiration (reason is unclear)
=increased rate (frequency) of breathing

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The inherent activity of inspiratory neurons with cell
bodies located in the medulla governs the normal
respiratory cycle how

by activating the diaphragm and

intercostal muscles to cause the lungs to inflate

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why do the inspirtaory neursons cease firing

The inspiratory neurons cease firing because of selflimitations
and inhibitory influence of expiratory
neurons also located in the medulla

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as expiration proceeds/elongations, what happens to the inspiratory cetner

As expiration proceeds, the inspiratory center becomes
progressively less inhibited and once again becomes
active

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the neurons of the respiratory centers are located where and form what

in the medully oblongata

from the rhymicity center

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what does the rhytmicitt center control

automatic breathing

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what are the 2 types of neurons in the respiratory center

Consists of interacting neurons that fire either during inspiration (I neurons) or
expiration (E neurons)

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activation of E neurons inhibit or active the I neurons

inhibit

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what are the 3 major collections of neurons in the respiratory center

1) dorsal respiratory group 2) pneumotaxic center 3) ventral respiratory center

the dorsal respiratory group neurons cause what (inspiration or expirmation)

innspiration

where is the dorsal respiratory group of neurons located and what is their sensation

``` Located in dorsal portion of medulla, with sensory termination of vagal and glossopharyngeal sensory nerves, which transmit signals from peripheral chemoreceptors, baroreceptors, and lung receptors ```

where is the pneumotaxic center neuronns location

in the sup portion of the pons

what do the neurons of the pnemotaxic center control and how

control breathinng pattern by limitinng duration of filling phase

where are the neuronns of the ventral respiratory group lcated

in the ventrtolateral part of the medulla

what is the main function of the neurons in the ventral respiratory group

Inactive during normal quiet breathing, but contributes extra respiratory drive (especially expiration) when needed invovled in forced expriationn and innspirtationn

chemical control of respirationn is achieved via what two chemicals

co2 and h+

true or false: Excess CO2 or H+ in blood acts indirectly on respiratory center itself

false | Excess CO2 or H+ in blood can act directly on respiratory center itself

Excess CO2 or H+ in blood greatly increases or decrases the strength of both inspiratory and expiratory signals to respiratory muscles

increases

Co2 and H+ Greatly increases the strength of (both inspiratory and expiratory) or just expiratory signals to respiratory muscles

both

at rest, what provudes the most imporatant respiratory stimulus

At rest, carbon dioxide pressure in arterial plasma provides the most important respiratory stimulus ex: small inncreases in Po2 in inspired air trigger large increases in minute ventilation

why do Small increases in PCO2 in inspired air trigger large increases in minute ventilation

because there is a very narror range for PCO2

does plasma acidity have an affect over minute ventilation?

yes Plasma acidity, which varies with the blood’s carbon dioxide content, exerts command over minute ventilation

a fall in ph signals and reflects what

A fall in blood pH signals acidosis and reflects carbon dioxide retention and carbonic acid formation

what happens to inspiratory activtiy as arterial pH declines and hydrogen ions accumulate

As arterial pH declines and hydrogen ions accumulate, inspiratory activity increases to eliminate carbon dioxide and reduce arterial levels of carbonic acid

which out of these 3 have a direct effect on respiratory center (o2, co2 or h+)

co2 and h+

which out of these 3 do not have significant direct effect on respiratory center (co2, o2 or H+)

trtue or false and explain: 02 has a direct effect on respiratory center

false: INDIRECT • Rather acts almost entirely on peripheral chemoreceptors located in carotid and aortic bodies à these in turn transmit nervous signals to respiratory center for control of respiration

explain how o2 has an indirect effect on the thee respiratory centr

• Rather acts almost entirely on peripheral chemoreceptors located in carotid and aortic bodies à these in turn transmit nervous signals to respiratory center for control of respiration

co2 and H+ directly stimulate what neuronal area

chemosensoitive ara located beneath ventral surface of medualla

what area is highly sensorite to changes in blood co2 and h+

neuronal area called chemosensitive area

what does stimulation of the chemosensitve area (area sensitive to co2 and h+) cause and result in

Stimulation of this area causes excitation of other portions of respiratory center • Results in increased rate and depth of breathing

sensory neurons in the chemosensotive neuronal area are mosttly stimulated by what

h+ ions (versus co2)

true or false; H+ ions have difficulty permeating blood-brain barrier (BBB) and blood-cerebrospinal fluid (CSF) barrier

true

explain the reason that altho the chemoreceptive area is more sensotive to H+ ions, blood pco2 actually has a bigger effect

becais eH+ ions have difficulty permeating blood-brain barrier (BBB) and blood-cerebrospinal fluid (CSF) barrier

which has a larger effect in stimulated chemosensotive area: change in blood H+ or change in blood PCo2 and why

blood pco2 becuase H+ has a hard time going thru BBB

CO2 has less direct effect in stimulating chemosensitive | area or more direct effect than H+ ions

less

CO2 has less direct effect in stimulating chemosensitive | area than H+ ions , so why does it have a larger effectt in stimulated the chemosensotive area

because but easily crosses blood-brain barrier | and blood-cerebrospinal fluid barrier

explain the effect of carbon dioxide on chemosensotive area

When blood PCO2 increases, PCO2 in interstitial fluid of medulla and cerebrospinal fluid increases. CO2 molecules in these fluids bind with H2O to form carbonic acid (H2CO3) H2CO3 dissociates into H+ and bicarbonate ion (HCO3-) H+ ions (those dissociating from H2CO3, not the freely circulating H+ ions outside the BBB) stimulate the sensory neurons in chemosensitive area.

what happens when the lungs become overinflated

When lungs become over-inflated, sensory stretch receptors located in bronchi and bronchioles are activated =Afferent sensory signals from stretch receptors feed back to dorsal respiratory group through vagus nerve à "switch off" inspiratory ramp signal à inspiration ceases =hering-breur inflation reflex

the hering breur inflation reflex is activated when and what does that prtect you from

Hering-Breuer reflex is activated when inflation or tidal | volume (VT) exceeds 1.5 L, i.e. protects lungs from overinflation

what are 2 locations of peripheral chemorecpros

1) carotid bodies | 2) aortic bodies

where are the carotid bpdoes located

Located bilaterally at | bifurcation of carotid arteries

explain the passageway of afferent nerves in the carotid bodies

Afferent nerve fibers pass through Hering's nerves =to glossopharyngeal nerve =to dorsal respiratory center.

where are aortic bodies located

located along the arch of aorta

where do the nerves pass in the aortic boddies

Afferent nerve fibers pass through vagus nerve = to dorsal respiratory center.

true or false: changes in PCO2 have a tremendous effect on alveolar ventilation

true

increases in blood PCO2 within the normal range (35-75) cause what incrase inn alveolar ventilation

1 to 8 fold increase

does changes in PCO2 or changes in blood pH s there a larger effect on alveolar ventilation

PCO@

sensitive to reduced oxygen pressures resides where

in peripheral chemorecptors

The carotid bodies monitors the state of arterial blood where/when

just | before it perfuses the brain

Decreased arterial PO2 increases | alveolar ventilation through what

aortic | and carotid chemoreceptor stimulation

decreased arterial PO2 through aortic amnd carotid chemorecptors causes what

increase in alveolar ventilation

what protects us from reduced oxygen pressure in inspired air

the carotid bodies n

Peripheral chemoreceptors also stimulate ventilation in | exercise because of what

increases in temperature, acidity, and | carbon dioxide and potassium concentrations

ADD SLIDES 21 AND 22

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true or false; Increase of CO2 and H+ also excites chemoreceptors and causes indirect effect on respiratory center

true

The indirect effect of CO2 and H+ through chemoreceptors has | the 2 following characteristics compared to their direct effect:

1) It is much less powerful (7 times less) than their direct effect on the respiratory center in the brain. Therefore, their indirect effect is often neglected. 2) It is much faster (5 times) than the direct effect, so it might play an important role in increasing the response time to CO2 at the onset of exercise

alveolar ventilation can increase collectively by what 3 factors

``` – Increased CO2 or PCO2 – Decreased O2 or PO2 – Decreased pH or increased blood H+ concentration ```

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after holding your breath for how long does the urge for inspiration come

40 s

where does the stimulus to breath com from after holding breath

The stimulus to breathe comes primarily from increased arterial PCO2 and H+ concentration – The breakpoint for breath holding = 50 mm Hg PCO2

what does hyperventilating before breath holding do tto PCO2

Hyperventilating before breath holding causes alveolar | PCO2 to decrease to 15 mm Hg

explain why Hyperventilating before breath holding causes alveolar PCO2 to decrease to 15 mm Hg

– A larger-than-normal quantity of carbon dioxide leaves the blood and arterial PCO2 decreases – Extends breath-holding duration until arterial PCO2 and/or H+ concentration cause the urge to breathe